离子交换法制备银天然CXN及热稳定性研究  

作　　者：程晓维[1] 钟鹰[1,2] 郭娟[1] 黄强 龙英才[1] 

机构地区：[1]复旦大学化学系上海市分子催化与新材料重点实验室 [2]昭通师范高等专科学校,云南昭通657000 [3]中非地质工程勘查研究院

出　　处：《中国非金属矿工业导刊》2004年第5期33-36,共4页China Non-Metallic Minerals industry

摘　　要：以铵离子交换、焙烧或酸交换等方法,对我国CXN天然沸石(STI型)进行改性,分别得到H-STI-Ⅰ和H-STI-Ⅱ沸石。用银离子交换、低温氮吸附等表征不同改性方法所得H-STI沸石的离子交换容量和吸附等性质。结果表明,不同改性方法产生的非骨架铝对孔道的堵塞及对阳离子交换位的屏蔽作用不同。铵交换后直接进行酸处理的样品离子交换度高,且孔道通畅、完美。以离子交换结合控制焙烧的方法分别制得结构超稳化高硅H-STI-Ⅲ和H-STI-Ⅳ沸石,分段程序升温焙烧后的沸石样品经粉末XRD表征表明其结构热稳定性达到1 000℃以上。交换产物Ag-STI-Ⅲ和Ag -STI-Ⅳ沸石热稳定性高达900℃。粉末XRD表征获得的银STI沸石相对低的表观结晶度是由于Ag+对X射线具有较大的吸收系数。A natural CXN zeolite (STI type) discovered in China was modified with the procedure of NH4+-exchange and thencalcination or with H+-exchange, to obtain H-STI-Ⅰand H-STI-Ⅱ, respectively. The capacity of ion exchange and the adsorption of theH-STI zeolite samples modified with different procedures were investigated with silver ion exchange and N2 adsorption at low temperature.The results indicate that the extra-framework aluminum, produced by the above-mentioned modification methods, plays various roles onthe blocking channels and the shielding effect to the exchangeable cations. The zeolite sample, modified by the procedure of ion exchangewith NH4+ followed by treating with acid, possesses higher ion exchange capacity as well as open and perfect pore systems. The samplesof ultra-stable high-silica H-STI-Ⅰand H-STI-Ⅱ zeolites were prepared by the method of ion-exchanges combined with controlledcalcinations. XRD investigations on the samples, prepared with the procedure of temperature-programming calcinations, prove that thestructure thermal stability of both samples reaches higher than 1 000℃. The Ag+ exchange products, Ag-STI-Ⅲ and Ag-STI-Ⅳ, are stillstable after calcination at 900℃. The apparent lower crystallinity of the Ag-STI zeolite samples is due to the high absorption coefficientof Ag+ to X-ray.

关 键 词：沸石 热稳定性 离子交换法 骨架铝 表征 改性方法 AG^+ 吸收系数 XRD 换位 

分 类 号：TD752.2[矿业工程—矿井通风与安全] TQ424[化学工程]